Gyro height velocity curves

[Mark E]

Questions to Birdy, and others:

How well does the following chart relate to your flying experience? There are height and speed combinations which won't give you time to drop it in safely in case of engine failure - how applicable is this chart to your machine? The blue area shows the height-velocity curve of a 'light gyroplane'.

(Chart from Dan Thomas - at homebuiltforum - Thanks!)



Mark

http://www.rotaryforum.com/forum/picture.php?albumid=10&pictureid=240

[WaspAir]

I tried to get similar information on this forum a while back, without too much success. See this thread:

http://www.rotaryforum.com/forum/showthread.php?t=20129

Maybe you'll have better luck. I'd still like the information, so I'll stay tuned.

[Oskar]

Mark,

I'll be able to land my lightweight GyroBee inside your blue area, but a two seater will need a much larger blue area. You can have a look at the MT03 HV curve on page 38 of their manual at http://www.auto-gyro.com/chameleon//outbox//public/6/Flughandbuch-32-090603.pdf

Jut be aware that the scale is metric.

Oskar

[Mark E]

Thanks Waspair - somehow I'd missed your thread (given the amount of time I spend here don't know how that happened!):rolleyes:

There is some good information in there, (to summarize a little - those who responded feel pretty safe if they are over 40 knots at any height, with Stan dropping in from 0 mph at 200 ft, ... and that all just happens to match the h/v curve I was looking at... but depends entirely on the machine and the conditions - Oskar's 20 mph from 100 ft is pretty handy to have)

replies excerpts below:


From Stan:

200 ft. minimum, I added power but the engine died. I immediately nosed her down and remember thinking airspeed..airspeed...I remember getting it to 45 mph, flared and just landed with a little thump.

From Oskar:

From 20mph I need about 100ft to land comfortably. Air speed at the start of the flair needs to be 30mph, any slower and the landing is bound to be less than soft.


From Phil:

new to a machine or rotor, I keep the speed above 45mph(40kts), untill I've had time to run through a power off glide and a few banks and flares to see how responsive the rotor is to loading and speed. My experience with the Bensen blades mirrors Stan's.

from Birdy:

And to be realistic, theres alot more to consider than H and V. As Phil states, machine, rotor, and weight combinations. Can you approch streight and land shallow, or dose it have to be a low AS steep decent onto a spot, is it ahead, to one side, or behind you...............? Wots the air do'n?? If your not sure, go higher, simple.

From Fiveboy:

Ok. I never fly below 40mph AS. I know I can land from any height if I have that. … When I see anything at the edge of 40 I nose her down and pick up AS.

From Helipaddy:

On my Dominator, I need 40 mph at the end of the glide to make the flare comfortable. any less and its a bit of work and timing to get it right. I think 0 airspeed and around 200 ft would be the limit in order to get 40 mph comfortably for the flare. best rate of climb on my machine appears to be 47mph. So I think its around 3ft to 40mph then 10ft to 55mph then up to 50 ft then back to 0 mph and 200 ft. And using a standard climb out speed of 50-55mph.

[freebird]

The chart in the "Rotorcraft Flying Handbook", starts at 300' and slopes to a 45 mph airspeed. I have seen that a sparrowhawk conversion (RAF) and a 2 place snobird will perform fine within this chart. As far as a light single place goes, I am sure it will be a much shorter curve.

Don't forget that this chart will vary according to density altitude.

[ckurz7000]

One more to add for my MT03 flown solo at 390 kg (860 lbs) all up weight:

From 150 feet AGL I can pick up enough speed to flair if I put the nose down aggressively. The airspeed gets up to about 60-70 km/h (37-43 mph, 32-38 kts)), which should give you the "nose" of the HV diagram.

These numbers are even a bit conservative, meaning you can do a nice job on flair and landing. If you're just interested in a no-damage kind of landing, you could probably shave off 50 feet in height and 5 km/h in speed.

The data given in the MT03 operations manual are *very* conservative.

-- Chris.

[Mark E]

Thanks Oskar - very interesting to me as I just took my 'introduction to gyros' flight in an MT03.

can't reproduce the chart here - but (converting) 300 ft needs 50 mph (100 m and 80 km/hr), and 150 ft needs 60 mph (50 m and 100 km/hr) .... and "safe at any height speed" is about 70 mph (110 km/hr).

[Mark E]

Thanks Freebird,

and thanks Chris - your figures do make the chart look very conservative!

[Mark E]

Another question on the topic - do gyros have an 'ace up the sleeve' advantage over helis at low level - say at low level flight a gyro is keeping the speed up to 40 mph - then pulls up into a steep rudder turn - ie therefore low and effectively at 0 AS - but does the added energy (increased RRPM) then add a greater safety margin?

[WaspAir]

Gyros don't have the "strip" of avoid-area for low level and high speed that you see along the bottom edge of helicopter H-V diagrams, because there is no need for transition time / settling room to enter autorotation. Other than that, I'd say energy is energy, whether you have it as height/speed or trade some of it for rpm, you haven't actually increased the total energy on board.

[Mark E]

energy is energy, whether you have it as height/speed or trade some of it for rpm, you haven't actually increased the total energy on board.

I think that means a gyro safely zooming along at 20 feet and 40 mph then cranking up to a 'banking stop' (please excuse my terminology..) is actually very (reasonably?) safe even though now at 80 feet with almost no airspeed - because he has that stored energy in his rotors?

[ckurz7000]

...can't reproduce the chart here - but (converting) 300 ft needs 50 mph (100 m and 80 km/hr), and 150 ft needs 60 mph (50 m and 100 km/hr) .... and "safe at any height speed" is about 70 mph (110 km/hr).

Yes, the data given in the MT03 manual are, in my opinion, "cover your ass" numbers for the manufacturer and too conservative for actual operations.

80 km/h is already a safe speed to flair and land. Being 300 feet up and flying at 80 km/h, you're in a perfectly safe position if the engine quits suddenly. And the "safe at any height" speed (nose of the HV diagram) is given as higher than either Vx or Vy! So that HV diagram is not really useful and limits the operational envelope unnecessarily.

-- Chris.

P.S.: One thing to keep in mind, though, when comparing with my numbers: my numbers are for 390 kg whereas the figures in the manual are for 450 kg. But still....

[WaspAir]

I think that means a gyro safely zooming along at 20 feet and 40 mph then cranking up to a 'banking stop' (please excuse my terminology..) is actually very (reasonably?) safe even though now at 80 feet with almost no airspeed - because he has that stored energy in his rotors?

Some of it went into his rotor, and some of it went into the potential energy from the altitude gain (with the mass of the entire aircraft and pilot lifted). The mass in typical gyro blades is not terribly high, and that limits how much you can realistically store by spinning them faster. For anyone who doubts the energy stored merely by climbing, imagine how it would feel to have the aircraft dropped on you from that height, and you'll get the idea. Some of the energy will be lost as well from friction/drag (you can't get 100% conversion efficiency). If you manage to pop yourself back and up above that blue region on your graph, you're still in a good energy state.

I don't see a great advantage over helicopters here merely from zooming. Helicopters have upper rpm limits (fairly close to normal operating rpm) that are potentially harmful to exceed, so that restricts the overspeed energy you can store in your rotating bits, but you can still convert speed to altitude in a zoom. The real advantage is in not having that low level avoid area on the diagram in the first place; high speed very close to the ground is not a good idea in a helicopter because you just can't react fast enough if things go pear shaped on you.

[scott heger]

A trained pilot should safely recover from zero airspeed at 300 feet in a single place . Depending on your skill set it can be done from much lower, but at 300',you will make it happen safely everytime.

Just realize when your airspeed indicator is reading zero, you could be in a tailwind situation, meaning your airspeed is actually less than zero, and it takes additional altitude than you normally would to recover, and the landing is going to be fast or hard.

Always keep situational awareness of the wind direction,and check for changing indicators(flags, dust, water waves)often.

Scott Heger, Laguna Niguel,Ca N86SH

[ckurz7000]

I think that means a gyro safely zooming along at 20 feet and 40 mph then cranking up to a 'banking stop' (please excuse my terminology..) is actually very (reasonably?) safe even though now at 80 feet with almost no airspeed - because he has that stored energy in his rotors?

Even though the energy is stored in the rotor from the bank/zoom, it doesn't help you much. First ans foremost because it isn't enough to get you safely on the ground. Remember, the rrpm decay back to normal in a a few seconds. On my MT03 with extruded aluminum rotor it takes 2 seconds to bleed off the excess energy.

Secondly, the excess rotational speed of the rotor doesn't help you get down, flair and land when the engine quits. And that's going to take more than 2 seconds to do anyway.

-- Chris.

[Passin' Thru]

grimwat. watch these two videos closely ...

http://www.youtube.com/watch?v=7YUHUAkXU48&feature=related

http://www.youtube.com/watch?v=3wPDeQkweNM&feature=related

[Resasi]

Ron is a master at the art of energy management. It's impressive to watch.

[Mark E]

Thanks Waspair Scott and Chris - I now understand a bit more - I'm getting smarter all the time!

Thanks Pete - that is a great example by Ron (love that short clip!) - I doubt I'll ever have time to develop the skills or nerve to do that.

[birdy]

Questions to Birdy, and others:
Sorry Mark, only just found it.
Seems everyone has it covered. ;)

And Ronny A., for a weekend hack, you seem to be getn the hang of it mate. :)
Just one point tho, why always rites?
I know the blades sound better wen you drop rite, but its actualy more efficiant to go left, and in a real EO, you dont always have a chose.

[helipaddy]

Hi Birdy
Why more efficiant to go left??

[Passin' Thru]

Hi Birdy
Why more efficiant to go left??

Coz' he's on the "udder side" of the equator! ¿Remember "coriolis"? :eek::twitch::lol::lol:

[Resasi]

Direction of rotor travel, advancing/retreating blade,asymmetry of lift?

[Passin' Thru]

Direction of rotor travel, advancing/retreating blade,asymmetry of lift?
Leigh, now that I've had my attempt at humour, I'll try a more sensible reply.;):sorry:
Birdy is correct; it is more efficient if you throw it in the direction of blade rotation, and makes less noise. It flaps less energy out of the rotor. It has to do with the rapid cyclic precession.
Subjectively, it usually "feels" better in one direction than the other due to a number of factors, direction of propeller rotation being one of them.:blabla:

[Resasi]

Pete my reply was in no way connected with your humor, which was recognized as such. It was in fact because the question had me racking my own brains as to why, hence my question mark.

I intuitively knew the answer however did have problems in articulating it, even to myself. I have found rotary aerodynamics to rather more complex than my simple grasp of fixed wing aerodynamics, a source of interested fascination, if a little frustrated by my slow grasp of the subject.

Birdy is far from the simple cowpoke he makes himself out to be and I admire the grasp he often demonstrates of the subject, together with his determined effort to be a know-it-all. Not a bad thing in your line of work David

[birdy]

Petes' pretty well on the coin.
Less inertia lost in moven the disc through cyclic inputs means more for flyn.
Youll notice theres much less stick pressure needed to hard left than hard rite, thats coz your cyclic input is less, even to get the same rate effect.
Power is different too.
Usualy those 180 flairs are dun at idle, so prop gyroscopic effects are minimal, but if you have a lefthand prop on full noise, the gyroscopic effect of the prop on the rotating machine actualy takes alot of weight off the rotor, so you dont even loose any alt.
You can do the zact same 180 as in Rons' vid and still be at your initial alt. [ spot 180]

Birdy is far from the simple cowpoke
Im a simple cow grower n proud ofit.
Iv dun it a million times Leigh, and its taken me a while to figure why the difference. ;)

[Resasi]

Which is why we, who will probably never have the opportunity to try it a million times, so very much appreciate the input from you, who has.:yo:

[Passin' Thru]

Usualy those 180 flairs are dun at idle, so prop gyroscopic effects are minimal, but if you have a lefthand prop on full noise, the gyroscopic effect of the prop on the rotating machine actualy takes alot of weight off the rotor, so you dont even loose any alt.
You can do the zact same 180 as in Rons' vid and still be at your initial alt. [ spot 180]

That's a fact! When you hit it right, you can get a bit of "hang time" from excess rotor speed, do a quick 180 pedal turn and scoot off in another direction without lossing any altitude.

When Chuck B. usta fly the LOH6 blades with the brass tip weights, one of his favorite tricks was to make a sharp, high-G turn and stop about 3 feet above the runway and play helicopter for a few seconds while the machine slowly settled as the excess rotor speed bleed off.

[Mark E]

Thanks to all ... here's a copy/paste a couple of comments by Birdy and Nicolas from the homebuiltplanes forum which I think are relevant and interesting (Hope you don't mind, Birdy and Nicolas)

From Birdy:

The following chart compares the safe zones between a Bell204 (red) and a very light autogyro (blue), not a fair comparison at all, but it shows that both have areas to avoid.

The size of the areas to avoid in any aircraft depends alot on the bloke on the stick.
Sum need plenty of room, while others seemingly dont have any restrictions.
It all comes down to 'time in type'.
Ill do demos for interested people of worst case sinarios of engine failures, where ill be at slow cruise down wind [ 30mph] at bout 20-40' and cut power.
Any speeds above 40mph, all the room i need is enuff to clear the ground with the blades while bankn into wind, ie; 13'.

[I]
how far can you squeeze that area down
Depends on the abilirty of the pilot, the machine, and the conditions mate.
Like i said, sumtimes the no such thing asa no go area. Other times you mite need as much as hundred feet.

A helicopter is no different from an autgyro in such situations except that it can take off again from the tiny spot; the gyro needs some room to run.
Agreed, but a heli and a gyro, flyn side by side, both at 40 kts, at 40', both have engine failurse.............., i know which one id want to be driven. [And yes, iv autoed both.] The gyro gives you much more time to aim.
Haven room to get the heli off again isnt much use wen the heli is sitn on its head.

From Nicolas:

As Birdy said depends on the pilot and the machine!!!! a good combination of the 2 and there is no such thing as a no go area on a gyro.

Don't forget a big area on the helicopter no go chart is REACTION TIME plus safety margins for the helicopter to land in one piece.... not for the pilot to survive. in a helicopter you need to lower the collective for the rotor to transition from power to autorotation.

The gyro is always auto-rotating and you can use the rotor as a parachute ( with higher descent rate of course and a big bank on touch down) but is survivable (for the pilot anyway.. not the machine) and it is a last option.
Gyros with high inertia shock absorbers ( long travel) can parachute down vertically with the machine still in one piece!!!!

On Birdy's example 40 knots 40 feet of the ground you have an engine failure:

Helicopter: helicopter breaks, pilot may or may not survive.
Gyro: gyro and pilot in one piece, even on some rough terrain (rough terrain May Damage the gyro)
Fixed Wing (airplane): 40 KNOTS AND 40' IT IS A NO GO AREA FOR 95% OF AIRPLANES EVEN BEFORE THE ENGINE FAILS!!! For the rest of the slow flying airplanes they are on the verge of stall and spin to the ground!!

the above are general probabilities... there are exceptions... you may slip and fall as you walk to your aircraft and die or you may stall and spin from 200 feet and survive!!!

I fly and own (some partly owned) almost all kinds of flying machines. Personally for me the order of safety is:

1, Gyro
2 Intermediate performance Glider (35:1 LD)
3, Airplane
4 trike
5 helicopter

[Resasi]

WOW!!

Once again it is great for us newbies to be able to get information like this from those amongst us that have the time and experience to give us information that is grounded on fact and actual experience.

I am aware that others are being careful and cautious for our own safety when advising us of considerably more height loss. But I was seriously doubting some of the figures I have heard being put about.

Yes as always it comes down to the experience of the person in the seat however it does allow us to know what we should be aiming to be able, with the time and practice, to possibly to achieve.

Great information. Thanks.

[Mark E]

I think I will just bear in mind the 40 mph speed at low level - (depending on machine ... )

and co-incidently - for Birdy's job - is just about the speed of a horse at a good gallop - so should be ideal for those bos indicus cattle he chases!

[gyrogreg]

Sorry I'm late getting into this thread - I don't have much time to keep up with the forum lately.

Here is an article published in Rotorcraft a couple years ago:

HV Curve for Gyroplanes (http://www.magnigyro.com/USA/feature_articles/HV%20Curve%20for%20Gyroplanes.pdf)

I got a lot of grief for this article from several instructors who seemed to claim there was no such thing as a HV curve for gyroplanes. Believe me HV is something you do need to pay attention to.

[mark treidel]

Thanks for the link Greg...
I read this article before and it certainly bears re-reading by all gyro pilots, if for nothing more than to raise personal awareness (in areas we tend to become complacent). This is one place that we should NOT press the envelope. Forewarned is Forearmed!!

[Fl90]

You don't chase cows at 40. And the hairy dicks want to play chicken and stick a horn in you. After all, they've never met anything bigger or badder than they are.

Stick to the 40+ at any altitude, you'll do fine. You pick your own chart for the machine you fly, if you're not sure then don't do it. If you are sure and wrong, it has to be your decision.

Phil